On Fri, 25 Feb 2005, Vig, Sandor (G/FI-2) wrote: > Hi, > > Another "funny" thing: I have a query which runs > on (Linux) PostgreSQL 7.4.x under 10 sec. I tried > to run it on (Windows) PostgreSQL 8.0 yesterday. > It didn't finished at all! (I shoot it down after 10 minutes) > I made various tests and I figured out something interesting: > The same query with: > A, "history.undo_action_id > 0" runs in 10 sec. > B, "history.undo_action_id is not null" runs in 10 sec. > C, "history.undo_action_id is null" runs forever (?!) > I used EXPLAIN but I couldn't figure out what the problem was.
EXPLAIN ANALYZE would be more useful. My first guess would be that the IS NULL is returning many more than the estimated 1 row and as such a nested loop is a bad plan. How many history rows match type_id=6 and undo_action_id is null? ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
